Monday, January 19, 2015

COPD exacerbation - definition, assessment, management

COPD
exacerbation:

Definition:

Exacerbation of COPD is defined as an acute episode,
characterized by the worsening of the patient’s respiratory symptoms that is
beyond normal daily variations and that will eventually lead to a change in his
medications.
Those having 2 or more exacerbations per year are known as
“frequent exacerbators”.

Precipitating
factors:

1) Respiratory tract infections – viral or bacterial.
Most common cause. There may be an increased bacterial burden in the lower
airways or new strains of bacteria are acquired during an exacerbation.
Commonly implicated viruses

Spirometry is difficult to perform during an exacerbation
and it may not be of enough accuracy. Therefore it is not recommended.

Treatment:

More than 80% of cases can be managed as outpatients but
if the following conditions are seen, it is better to admit and if necessary
give intensive care:

1) Dyspnea occurring at rest

2) Old age

3) Frequent exacerbator

4) Failure of response to change in/addition of
medication to control the exacerbation

5) New onset of arrhythmias or peripheral edema.

Medical therapy
consists of:

1) Short acting inhaled bronchodilators – beta-2 agonists
with or without anti-cholinergics are preferred. It is better to use a
nebulizer as the patient usually is dyspneic and lacks coordination to inhale
from a metered-dose inhaler. IV methylxanthines are considered as second line
of therapy for bronchodilation and are to be used only in selected cases,
especially if there is poor response to short acting inhaled bronchodilators.

2) Corticosteroids – oral prednisone 40 mg/day for 5 days
has been shown to shorten recovery time and improve lung function as well as
arterial hypoxemia.

3) Antibiotics – these are indicated if the patient has
clinical signs of bacterial infections e.g. increased in sputum purulence. Procalcitonin III may help to indicate
antibiotic therapy as it is increased in cases of bacterial infections. Usually
in the following conditions antibiotics should be considered:

4) Adjunct therapies – proper control of comorbidities is
advised. Thromboprophylactic measures should be enhanced.

Respiratory support:

1) Oxygen therapy: Oxygen is titrated to correct the
hypoxemia of the patient aiming to achieve a saturation of 88-92%. Usually Venturi
masks are preferred to nasal prongs. After 30-60 minutes of oxygen therapy,
arterial blood gases should be checked.

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